Bismuth telluride / laser-induced graphene-based thermoelectric power generation device and preparation method thereof

Abstract

The invention provides a bismuth telluride / laser-induced graphene-based thermoelectric power generation device and a preparation method thereof. The thin-film-shaped flexible bismuth telluride / laser-induced graphene thermoelectric power generation device comprises a PI substrate, an LIG layer printed on PI by using CO2 laser, P-type and N-type bismuth telluride materials alternately coated on LIG, finally secondary ablation is performed on the bismuth telluride materials by using CO2 laser, and then each thermoelectric module is connected through a conductive silver adhesive, so that the thin-film-shaped flexible bismuth telluride / laser-induced graphene thermoelectric power generation device is integrally formed. The manufacturing method is simple and convenient, the manufacturing cost of the bismuth telluride-based thermoelectric power generation device is greatly reduced, and the obtained device is light and thin, can be bent and twisted, has good durability, can be patterned and customized, and has wide application prospects in monitoring human body temperature changes, collecting waste heat in scenes such as homes and factories and the like and early warning fire disasters.

Description

This invention relates to the field of flexible thermoelectric power generation devices and fabrication methods based on bismuth telluride / laser-induced graphene (LIG). Background Technology

[0002] With the continuous growth of global energy consumption, energy efficiency and environmental sustainability have become key issues restricting development. A large amount of low-grade heat energy exists in industrial production, power transmission, and everyday home environments that is not effectively utilized. In-situ recovery and utilization of this waste heat would be of great significance in alleviating the energy crisis. Thermoelectric generation (TEG) technology utilizes the Seebeck effect to directly convert heat energy into electricity, offering significant advantages such as being all-solid-state, maintenance-free, and noiseless, making it an ideal solution for recovering lost heat energy and achieving self-driven sensing. However, while traditional inorganic thermoelectric materials have superior performance, their brittle nature limits their application in non-planar (e.g., high-temperature pipes, irregularly shaped heat sources) and flexible scenarios. Therefore, developing flexible thermoelectric devices with high energy conversion efficiency and good conformability to heat source surfaces has become a research hotspot in the field of heat harvesting and management.

[0003] Meanwhile, stringent requirements are being placed on the long-term reliability of sensors in complex physical environments for industrial fire early warning, home safety monitoring, and extreme environmental temperature monitoring. While existing ion-gel thermoelectric devices offer advantages in sensitivity, they are susceptible to moisture evaporation, ion polarization, and environmental interference during high-temperature, low-humidity, or long-term operation, leading to signal drift or performance degradation, making it difficult to meet the long-term stability requirements of "industrial-grade" fire monitoring. In contrast, electronic thermoelectric materials, represented by bismuth telluride (Bi₂Te₃), are increasingly regarded as promising flexible thermoelectric materials by universities and research institutions due to their excellent charge carrier transport characteristics and physicochemical stability. By microscale composites of high-thermoelectric-performance bismuth telluride with laser-induced graphene (LIG) scaffolds possessing excellent mechanical toughness, not only can the brittle fracture problem of inorganic materials be solved, but the device can also maintain stable linear voltage output under thousands of bends and severe temperature fluctuations. This flexible all-solid-state device, combining efficient energy recovery and accurate temperature difference early warning, has significant application value for building all-weather, long-life self-driven fire monitoring networks.

[0004] In existing research on flexible thermoelectric devices, ionic thermoelectric materials (such as ionogels) have attracted attention due to their high thermoelectric potential, but they still face many challenges in practical applications. For example, patent CN115697014A, which describes an ionic hydrogel, an ionic thermoelectric device, its preparation method, and its application, uses ions as charge carriers within its ionic material. Under continuous temperature differences, ionic polarization easily occurs, causing the output voltage to decay over time, making it unsuitable as a stable power supply. Secondly, the liquid electrolyte contained in its ionogel is prone to solvent evaporation or drying in high-temperature industrial waste heat environments or dry environments, leading to device failure. Furthermore, its performance is greatly affected by fluctuations in environmental humidity, failing to meet the stringent requirements of "high reliability and zero error" for sensors in safety monitoring fields such as fire early warning.

[0005] On the other hand, in pursuit of higher stability, some studies have attempted to composite high-performance inorganic thermoelectric materials (such as bismuth telluride and bismuth antimonide) with organic polymers or other substrates. However, traditional composite strategies often employ simple mechanical-physical mixing, resulting in poor interfacial affinity between the inorganic active material and the flexible substrate, as seen in patents CN117320532A (Cu(selenide)-based thermoelectric materials, their preparation methods, and applications) and CN115955903A (a bismuth telluride-based thermoelectric device encapsulation structure and its preparation method). This not only leads to significant barrier losses for charge carriers during cross-interface transport, increasing the device's internal resistance, but also causes brittle inorganic particles to easily detach from the flexible support or generate microcracks during frequent mechanical bending, resulting in irreversible and severe degradation of the device's thermoelectric performance. Therefore, how to achieve deep integration of inorganic materials with the flexible framework at the atomic or nanoscale while maintaining high thermoelectric conversion efficiency is a bottleneck problem that urgently needs to be solved in the field of high-performance flexible thermoelectric devices.

[0006] In summary, there is an urgent need for an all-solid-state flexible thermoelectric device that combines high stability, high thermoelectric performance, and excellent mechanical toughness to solve the problems of easy polarization decay, environmental sensitivity, and large interface loss of inorganic composite devices in the existing technology. To address the aforementioned technical problems, this invention provides a thermoelectric power generation device based on bismuth telluride / laser-induced graphene and its preparation method. This device features flexibility, high sensitivity, strong durability, high thermoelectric performance, and simple preparation steps, and has significant application value.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: a thermoelectric power generation device based on bismuth telluride / laser-induced graphene and its preparation method, comprising the following steps: (1) cutting a polyimide (PI) film into the required shape, then wiping its surface with ethanol, and fixing it to a glass plate with a hydrosol to obtain a flat and clean PI film; (2) inducing a three-dimensional porous graphene foam (LIG) from the flat and clean PI film obtained in step (1) using a CO2 laser to obtain a conductive laser-induced graphene substrate, which is reserved for later use; (3) ... Unprocessed P-type and N-type bismuth telluride powders were mixed with appropriate amounts of n-hexane and added to an agate grinding jar. Zirconia grinding balls of different sizes were added in a certain mass ratio and ball milled in a star-shaped ball mill to obtain finer bismuth telluride powder (with n-hexane residue); (4) The bismuth telluride powder obtained in step (3) was washed with ethanol and the powder and liquid were separated by a vacuum filter. The separated powder was dried to finally obtain fine-particle-size, dry, and pure bismuth telluride powder; (5) PI tape of the corresponding size was attached to a glass plate and the phase was cut out using a laser printer. (6) Take out an appropriate amount of bismuth telluride powder obtained in step (4), grind it into a fine and distinct powder in an agate grinding bowl, and mix it with ethanol, ethylene glycol and dispersant in a certain mass ratio; (7) Put the mixture in step (6) into an ultrasonic cell disruptor for ultrasonic dispersion treatment for a certain time and power, put the treated mixture into a magnetic stirrer, evaporate the excess ethanol, and obtain a fine and smooth bismuth telluride slurry; (8) Take the bismuth telluride powder obtained in step (5) The mask is applied to the LIG substrate obtained in step (2), and the P-type and N-type bismuth telluride pastes obtained in step (7) are alternately coated on the corresponding LIG areas using a four-legged press, and allowed to air dry naturally; (9) the bismuth telluride coated on the LIG obtained in step (8) is subjected to secondary ablation at a certain laser power and speed to obtain a thermoelectric power generation module with alternating P and N types; (10) the thermoelectric power generation module obtained in step (9) is connected with conductive silver paste and wires are bonded to obtain a flexible thermoelectric power generation device based on bismuth telluride / LIG.

[0009] In the above scheme, the laser for printing LIG in step (2) is provided by a CO2 laser with a wavelength of 10.6μm. The laser power used by the laser is 3.6-5.4W, the laser scanning speed is 127-203.2mm / s, and the laser is induced by the grating method.

[0010] Furthermore, in step (3), the mass ratio of bismuth telluride powder to n-hexane is 25:66, and the mass ratio of powder to grinding balls is 1:20; the ball milling parameters of the planetary ball mill are 600-700 r / min, and the ball milling is performed for 3 hours with a duty cycle of 10:10.

[0011] Furthermore, the PI tape in step (5) is 75μm thick, the laser printer uses vector mode for cutting, the laser power is 2.4-3.6W, and the laser scanning speed is 114.3-177.8mm / s.

[0012] Furthermore, the mass ratio of bismuth telluride powder, ethanol, ethylene glycol and dispersant in step (6) is 85:13:1:1.

[0013] Furthermore, in step (7), the ultrasonic power of the ultrasonic cell disruptor is 360-450W, and the ultrasonic treatment is performed for 20-45 minutes with a duty cycle of 2:2.

[0014] Furthermore, in step (9), the laser used for secondary ablation is a CO2 laser with a wavelength of 10.6 μm. The laser power used is 7.5 W-13.5 W, the laser scanning speed is 165.1-254 mm / s, and the secondary ablation is performed using a grating method.

[0015] The flexible thermoelectric power generation device based on bismuth telluride / laser-induced graphene provided by this invention has Seebeck coefficients of 162.45 μV / K for P-type devices and -178.39 μV / K for N-type devices, and 357.8 μV / K for the thermoelectric power generation device after forming a PN junction; when the temperature difference is 3K, the power density of the thermoelectric power generation device is 3.81 mW / m². 2 This device can also generate electricity or detect temperature with a small temperature difference, with a detection limit as low as 0.1℃. It also achieved normal operation after more than 10,000 bending cycles, verifying its long-term stability. This device also has good thermoelectric performance, high sensitivity, and uses a flexible substrate, which has good durability and stability.

[0016] Compared with existing thermoelectric devices and fabrication methods, the advantages of this invention are as follows: The thermoelectric layer of this invention adopts a bismuth telluride / LIG composite system, utilizing the excellent charge transport capability and chemical stability of electronic thermoelectric materials to fundamentally solve the problems of ion polarization decay and solvent evaporation existing in ionic thermoelectric materials. It also solves the problem of excessive rigidity caused by traditional composite methods for other inorganic thermoelectric materials. As a high-performance solid-state semiconductor thermoelectric material, bismuth telluride exhibits a Seebeck effect stemming from the directional migration of charge carriers (electrons or holes) driven by temperature differences. It possesses significant advantages such as high output voltage linearity, fast response speed, and no signal drift during continuous operation, effectively avoiding the risk of leakage during device use and greatly improving the device's lifespan and reliability in industrial high-temperature waste heat recovery and harsh environmental monitoring.

[0017] This invention utilizes laser-induced graphene (LIG) with a unique three-dimensional porous honeycomb structure, laser-induced on a polyimide (PI) substrate, to provide a high specific surface area loading space for the bismuth telluride active material. This achieves a high degree of integration between the thermoelectric material and the conductive framework, effectively reducing interfacial contact resistance. Simultaneously, the excellent mechanical toughness of LIG effectively alleviates the brittleness of the bismuth telluride material, ensuring that the conductive network maintains a high degree of continuity even under bending, torsion, or mechanical strain. Utilizing this characteristic, the device not only achieves efficient heat recovery but also has broad application prospects in industrial fire early warning and equipment health monitoring. Attached Figure Description

[0018] Figure 1 is a flowchart illustrating the fabrication process of a flexible thermoelectric generator based on bismuth telluride / laser-induced graphene according to an embodiment of the present invention; Figure 2 is a structural schematic diagram of a flexible thermoelectric generator based on bismuth telluride / laser-induced graphene according to an embodiment of the present invention; Figure 3 is a schematic diagram illustrating the thermoelectric power generation and temperature sensing working principle of an N-type flexible thermoelectric generator based on bismuth telluride / laser-induced graphene according to an embodiment of the present invention; Figure 4 is a P-type flexible thermoelectric generator based on bismuth telluride / laser-induced graphene according to an embodiment of the present invention. Figure 5 shows the output voltage variation of an N-type flexible thermoelectric generator based on bismuth telluride / laser-induced graphene according to an embodiment of the present invention at different temperature differences; Figure 6 shows the fitted temperature difference output voltage diagram of a flexible thermoelectric generator based on bismuth telluride / laser-induced graphene according to an embodiment of the present invention. From the diagram, the Seebeck coefficients of the P-type and N-type devices are calculated to be 161.65 μV / K and -174.87 μV / K, respectively; Figure 7 shows the output voltage variation of an N-type flexible thermoelectric generator based on bismuth telluride / laser-induced graphene according to an embodiment of the present invention at different temperature differences. Figure 8 shows the voltage curve generated by the P-type flexible thermoelectric generator based on bismuth telluride / laser-induced graphene in one embodiment of the present invention at the lowest temperature difference of 0.1℃; Figure 9 shows the thermoelectric power generation and temperature sensing schematic diagram of the PN-type flexible thermoelectric generator based on bismuth telluride / laser-induced graphene in one embodiment of the present invention; Figure 10 shows the power density diagram of the PN-type flexible thermoelectric generator based on bismuth telluride / laser-induced graphene in one embodiment of the present invention; Figure 11 shows the output voltage change of the PN-type flexible thermoelectric generator based on bismuth telluride / laser-induced graphene in one embodiment of the present invention at different temperature differences; Figure 12 shows the resistance change curve of the PN-type flexible thermoelectric generator based on bismuth telluride / laser-induced graphene in one embodiment of the present invention after more than 10,000 bends; Figure 13 shows the voltage curve generated by the PN-type flexible thermoelectric generator based on bismuth telluride / laser-induced graphene in one embodiment of the present invention before and after human movement. Detailed Implementation

[0019] The following specific embodiments further illustrate this solution. The descriptions in the embodiments are only for explaining the solution of the present invention and are not intended to limit the present invention. In the following embodiments, unless otherwise specified, all materials involved are commercially available. For example, the polyimide film used in the embodiments is a preferred film from China Maikesi Company; the bismuth telluride powder was purchased from Zhongke Yannuo (Beijing) Technology Co., Ltd.; sodium carboxymethyl cellulose (dispersant) was purchased from Sinopharm Chemical Reagent Co., Ltd.; the glass plates, hydrosols, conductive silver paste, and wires used are also conventional types and can all be purchased from the market.

[0020] The flexible thermoelectric power generation device based on bismuth telluride / laser-induced graphene (LIG) described in this invention exhibits excellent thermoelectric conversion performance. Due to the use of a laser-induced secondary ablation process, the bismuth telluride powder and the LIG substrate achieve a tighter physical bond, effectively reducing the device's internal resistance. Experimental results show that the device can generate a significant voltage output even with a small temperature difference, with a temperature difference detection limit as low as 0.1℃, and exhibits extremely high linearity between the output voltage and the temperature difference. Under continuous heating and high-temperature industrial environments, the device demonstrates the stability characteristic of electronic thermoelectric materials, exhibiting no signal drift or polarization attenuation, and can serve as a long-term self-powered energy source for small electronic devices.

[0021] Meanwhile, the three-dimensional porous structure of LIG provides excellent mechanical support for bismuth telluride, enabling the device to maintain stable initial resistance and sensitive response characteristics even after undergoing bending, torsion, or tensile deformation (more than 10,000 cyclic bending tests), verifying its excellent durability and long-term stability. Through a stable thermoelectric output signal, this device can achieve thermoelectric power generation and temperature change monitoring, which has significant application value in human health monitoring, industrial waste heat collection, and fire (high temperature) early warning.

[0022] Example 1: A thermoelectric power generation device based on bismuth telluride / laser-induced graphene and its preparation method, including the following steps: (1) A 200 μm thick polyimide (PI) film is cut into a 100 mm × 100 mm shape, and then its surface is wiped with ethanol and fixed to a glass plate with hydrosol to obtain a flat and clean PI film; (2) The flat and clean PI film obtained in step (1) is induced to form a three-dimensional porous graphene foam (LIG) by a CO2 laser in grating mode. The LIG pattern is a 20 mm × 5 mm rectangle to obtain a conductive laser-induced graphene substrate, which is reserved for later use; the grating mode laser is provided by a CO2 laser with a wavelength of 10.6 μm and the laser power used by the laser is 4 .2W, laser scanning speed is 127mm / s; (3) Mix 25g of raw, unprocessed P-type and 25g of N-type bismuth telluride powder with 100ml of n-hexane and add them to an agate grinding jar, and add 500g of zirconium oxide grinding balls of different sizes. Grind them in a planetary ball mill at 700r / min and a duty cycle of 10:10 for 3h to obtain finer bismuth telluride powder (with a small amount of n-hexane residue); (4) Wash the bismuth telluride powder obtained in step (3) with ethanol and separate the powder and liquid with a vacuum filter. Place the separated powder in an oven and dry it at 60℃ for 30min to finally obtain fine-particle-size, dry, and pure bismuth telluride powder; (5) Adhere a 75μm thick PI tape to a glass plate and use The laser printer uses vector mode for cutting, so that when it is attached to the substrate obtained in step (1), the LIG part can be exposed. After cutting, it is removed from the glass plate for use when coating bismuth telluride slurry. The vector mode laser is provided by a CO2 laser with a wavelength of 10.6 μm. The laser power used by the laser is 3W and the laser scanning speed is 114.3 mm / s. (6) Take out an appropriate amount of bismuth telluride powder obtained in step (4), grind it into a fine and distinct powder in an agate grinding bowl, and mix it with ethanol, ethylene glycol and dispersant in a mass ratio of 85:13:1:1. (7) Put the mixture in step (6) into an ultrasonic cell disruptor with a power of 396W and a duty cycle of 2:2. The mixture was ultrasonically dispersed for 30 minutes. The mixture was then placed in a magnetic stirrer to evaporate excess ethanol, resulting in a fine and smooth bismuth telluride slurry. (8) The mask obtained in step (5) was applied to the LIG substrate obtained in step (2), and the P-type and N-type bismuth telluride slurries obtained in step (7) were alternately coated onto the corresponding LIG areas using a four-legged press, and allowed to air dry naturally. (9) The bismuth telluride coated onto the LIG in step (8) was subjected to secondary ablation in grating mode to obtain a thermoelectric power generation module with alternating P and N types. The vector mode laser was provided by a CO2 laser with a wavelength of 10.6 μm. The laser power used by the laser was 9.9 W, and the laser scanning speed was 203.2mm / s; (10) Connect the thermoelectric power generation module obtained in step (9) with conductive silver paste and bond the wires. The thermoelectric particles move towards both ends of the sensor as the temperature changes, and the generated voltage increases as the temperature difference between the left and right ends increases, thus obtaining a flexible thermoelectric power generation device based on bismuth telluride / laser-induced graphene.

[0023] The fabrication process of the flexible thermoelectric generator based on bismuth telluride / laser-induced graphene is shown in Figure 1. The device is a thin-film tandem structure, as shown in Figure 2. A CO2 laser is used to induce LIG to form a three-dimensional porous network on the PI film using a grating method. After coating the surface with bismuth telluride paste, a second ablation is performed using a laser to achieve deep composite of bismuth telluride and LIG, resulting in a high-performance, long-term stable, and flexible thermoelectric generator that can be bent at will.

[0024] Figure 3 is a schematic diagram illustrating the working principle of the N-type thermoelectric device based on bismuth telluride / laser-induced graphene according to an embodiment of the present invention. When a temperature gradient exists between the two ends of the device, charge carriers (electrons) inside the bismuth telluride active layer migrate directionally from the high-temperature end to the low-temperature end and accumulate at the cold end, thereby generating a potential difference, i.e., a thermoelectric voltage, between the two ends of the device. Simultaneously, when there is a temperature change at any end of the device, the voltage across the device will change, thus achieving temperature sensing.

[0025] Figures 4 and 5 show the output voltage curves of the P-type and N-type thermoelectric modules prepared according to embodiments of the present invention under different temperature gradients. As can be seen from the experimental curves, with the increase of the temperature difference between the hot and cold ends, the open-circuit voltage output by the device exhibits a significant step-like increase, and the voltage signal response is rapid with a stable baseline. Figure 6 shows the temperature difference-voltage linear relationship obtained by fitting the data from Figures 4 and 5, i.e., the Seebeck coefficient. Through linear fitting calculation, the Seebeck coefficients of the P-type and N-type devices are 161.65 μV / K and -174.87 μV / K, respectively. Figures 7 and 8 show that the experimentally measured temperature difference detection limit of the device near room temperature can reach 0.1℃, demonstrating its ultra-high sensitivity under small temperature differences, sufficient for capturing weak temperature differences on the human skin surface or for primary fire early warning in industrial environments.

[0026] In the output power characteristic test, a thermoelectric array was formed by connecting P-type and N-type devices in series, and a variable load resistor R was connected in the circuit. out Its equivalent circuit and test schematic are shown in Figure 9. According to the power calculation formula P=U... 2 / R out The power characteristic curve of the device is shown in Figure 10. When the load resistance and the device's internal resistance R... i The device achieves maximum power density when impedance matching is reached. Thanks to the continuous, high-conductivity three-dimensional transmission network provided by LIG, the device's internal resistance is effectively suppressed, thus achieving 3.81 mW / m² at a small temperature difference of 3 K.2 The high power density output provides a foundation for industrial-grade waste heat collection and energy supply. Figure 11 further illustrates the voltage output of the PN array under combined temperature differences, showing that by connecting multiple units in series, the voltage gain of the device is significantly improved, effectively driving low-power electronic components.

[0027] To verify the long-term reliability and mechanical durability of the device, cyclic bending tests were conducted. Figure 12 shows the resistance change curve of the device after more than 10,000 bends. Under repeated bending, the device resistance fluctuation was minimal, which fully demonstrates that the laser secondary ablation process creates a deep composite interface between bismuth telluride and LIG with extremely strong interfacial bonding force, effectively resisting delamination or fracture caused by deformation, showcasing its excellent cyclic stability and durability. Figure 13 shows the voltage dynamic response curve of the device monitoring the subject's body temperature changes before and after exercise. Before exercise, the temperature difference between the subject's body temperature and the ambient temperature was 3.6℃, ​​which increased to 4.5℃ after exercise due to the rise in body temperature. The results show that as body temperature rises after exercise, the temperature difference voltage detected by the device increases significantly, and the voltage signal can reflect the trend of body temperature fluctuations in real time and accurately, demonstrating its practical application value in the field of human health monitoring.

[0028] Comparative Example 1: A 200 μm thick polyimide (PI) film was cut into 100 mm × 100 mm shapes. After wiping its surface with ethanol, it was fixed to a glass plate using a hydrosol, resulting in a smooth and clean PI film. This smooth and clean PI film was then used to induce three-dimensional porous graphene foam (LIG) using a CO2 laser in grating mode. The LIG pattern consisted of 20 mm × 5 mm rectangles, resulting in a conductive laser-induced graphene substrate, which was reserved for later use. The grating mode laser was provided by a 10.6 μm wavelength CO2 laser with a laser power of 3 W and a laser scanning speed of 127 mm / s. This laser power parameter was too low to produce a uniformly carbonized, high-quality LIG, making it unsuitable as a LIG substrate.

[0029] In Comparative Example 2, after printing a high-quality and compliant LIG on a PI film using preferred laser parameters, bismuth telluride slurry was coated onto the LIG substrate using a mask and a four-pin press, following the steps in Example 1, and allowed to air dry. The bismuth telluride coated onto the LIG obtained in the above steps was then subjected to secondary ablation in grating mode to obtain a thermoelectric power generation module with alternating P and N-type configurations. The vector mode laser was provided by a 10.6 μm wavelength CO2 laser with a laser power of 15 W and a laser scanning speed of 203.2 mm / s. This laser power parameter was too high, causing the bismuth telluride powder to sublimate directly or sputter from the LIG substrate, resulting in a decrease in the Seebeck coefficient of the device and an inability to generate an effective thermoelectric voltage. Several embodiments of the present invention have been described above, but the content described is only a preferred embodiment or comparative example of the present invention and should not be considered as limiting the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

[0030] Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A method for fabricating a thermoelectric power generation device based on bismuth telluride / laser-induced graphene, characterized in that, The process includes the following steps: Step 1: Cut the polyimide film (PI film) into the desired shape, wipe its surface with ethanol, and then fix it to a glass plate with hydrosol to obtain a smooth and clean PI film; Step 2: Induce three-dimensional porous graphene foam (LIG) from the smooth and clean PI film obtained in Step 1 using a CO2 laser to obtain a conductive laser-induced graphene substrate, which is then reserved for later use; Step 3: Mix unprocessed P-type and N-type bismuth telluride powders with appropriate amounts of n-hexane and add them to the substrate. The bismuth telluride powder is placed in an agate grinding jar and zirconia grinding balls of different sizes are added in a certain mass ratio. It is then ball-milled in a star-shaped ball mill to obtain finer bismuth telluride powder. Step 4: The bismuth telluride powder obtained in Step 3 is washed with ethanol, and the powder and liquid are separated using a vacuum filter. The separated powder is then dried to obtain fine-particle-size, dry, and pure bismuth telluride powder. Step 5: PI tape of the appropriate size is adhered to a glass plate. A mask of the corresponding shape is cut out using a laser printer and removed from the glass plate for coating. Used in bismuth telluride slurry; Step 6: Take an appropriate amount of bismuth telluride powder obtained in step 4, grind it into a fine and distinct powder in an agate grinding mortar, and mix it with ethanol, ethylene glycol and dispersant in a certain mass ratio; Step 7: Put the mixture in step 6 into an ultrasonic cell disruptor for ultrasonic dispersion treatment for a certain time and power, put the treated mixture into a magnetic stirrer to evaporate excess ethanol, and obtain a fine and smooth bismuth telluride slurry; Step 8: Apply the mask obtained in step 5 to the bismuth telluride slurry obtained in step 2. Step 7 involves applying the P-type and N-type bismuth telluride pastes obtained in step 8 to the corresponding LIG regions using a four-legged film press, and then allowing them to air dry naturally. Step 8 involves subjecting the bismuth telluride coated on the LIG in step 8 to a secondary ablation at a certain laser power and speed to obtain a thermoelectric power generation module with alternating P and N types. Step 9 involves connecting the thermoelectric power generation modules obtained in step 9 with conductive silver paste and bonding wires to obtain a flexible thermoelectric power generation device based on bismuth telluride / LIG.

2. The method for fabricating a thermoelectric power generation device based on bismuth telluride / laser-induced graphene according to claim 1, characterized in that, In step 2, the laser used to print LIG is a CO2 laser with a wavelength of 10.6 μm. The laser power used is 3.6-5.4 W, the laser scanning speed is 127-203.2 mm / s, and the laser is induced by the grating method.

3. The method for fabricating a thermoelectric power generation device based on bismuth telluride / laser-induced graphene according to claim 1, characterized in that, In step 3, the mass ratio of bismuth telluride powder to n-hexane is 25:66, and the mass ratio of powder to grinding balls is 1:

20. The ball milling parameters of the planetary ball mill are 600-700 r / min, and the ball milling is carried out for 3 hours with a duty cycle of 10:

10.

4. The method for fabricating a thermoelectric power generation device based on bismuth telluride / laser-induced graphene according to claim 1, characterized in that, The PI tape in step 5 is 75μm thick. The laser printer uses vector mode for cutting, and the laser power used is 2.4-3.6W, with a laser scanning speed of 114.3-177.8mm / s.

5. The method for fabricating a thermoelectric power generation device based on bismuth telluride / laser-induced graphene according to claim 1, characterized in that, The mass ratio of bismuth telluride powder, ethanol, ethylene glycol and dispersant in step 6 is 85:13:1:

1.

6. The method for fabricating a thermoelectric power generation device based on bismuth telluride / laser-induced graphene according to claim 1, characterized in that, In step 7, the ultrasonic cell disruptor has an ultrasonic power of 360-450W and operates at a duty cycle of 2:2 for 20-45 minutes.

7. The method for fabricating a thermoelectric power generation device based on bismuth telluride / laser-induced graphene according to claim 1, characterized in that, The laser used for secondary ablation in step 9 is a CO2 laser with a wavelength of 10.6 μm. The laser power used is 7.5 W-13.5 W, the laser scanning speed is 165.1-254 mm / s, and the secondary ablation is performed using a grating method.

8. A flexible thermoelectric power generation device based on bismuth telluride / laser-induced graphene, characterized in that, It is prepared by the method described in any one of claims 1-7.

9. The flexible thermoelectric generator based on bismuth telluride / laser-induced graphene according to claim 8, characterized in that, In the aforementioned flexible thermoelectric power generation device based on bismuth telluride / laser-induced graphene, the P-type and N-type devices have Seebeck coefficients of 162.45 μV / K and -178.39 μV / K, respectively, while the thermoelectric power generation device with a PN junction has a Seebeck coefficient of 357.8 μV / K. When the temperature difference is 3 K, the power density of the thermoelectric power generation device is 3.81 mW / m². 2 .

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